MySQL Proxy is a lightweight middleware that sits between the client and the MySQL server, allowing you to intercept, inspect, and modify the communication between them. It's often used for load balancing, query filtering, or as a gateway for security and access control. Here's a guide on how to configure MySQL Proxy for basic usage.

1. Installing MySQL Proxy

Before you can configure MySQL Proxy, you need to have it installed on your system. The installation process varies depending on your operating system. For Linux distributions, you can often find MySQL Proxy in the package repositories or download it from the MySQL website.

Once downloaded, you'll need to compile and install MySQL Proxy from source if you're using a tarball. Follow the instructions provided in the official documentation.

2. Creating the Configuration File

MySQL Proxy uses a Lua script as its configuration file. This script defines the behavior of the proxy, including which servers it should route queries to, any query rewriting rules, and any other advanced functionality.

A basic configuration file might look like this:

lua

In this example, the proxy is configured to connect to two backend MySQL servers. The proxy.default_query_rules section defines the default routing behavior, which in this case is to send all queries to the master server (assuming you have a Lua script named proxy.lua that defines the is_master function).

3. Writing Lua Scripts

MySQL Proxy's flexibility comes from its ability to execute Lua scripts that can inspect and modify queries. You can write Lua scripts to implement complex routing logic, query rewriting, or even custom authentication mechanisms.

The proxy.lua script in the example above would need to define the is_master function to determine which server is the master. This function would typically inspect the query or use some other logic to make the decision.

4. Starting MySQL Proxy

Once you have your configuration file and any necessary Lua scripts in place, you can start MySQL Proxy by passing the configuration file as an argument:

bash

In this command, --proxy-address specifies the address and port that MySQL Proxy should listen on, and --proxy-backend-addresses lists the addresses of the backend MySQL servers. --proxy-lua-script points to your Lua script.

5. Testing the Configuration

After starting MySQL Proxy, you can test your configuration by connecting to it using a MySQL client and executing some queries. You should see the queries being routed to the appropriate backend server based on your Lua script and configuration file.

6. Monitoring and Troubleshooting

MySQL Proxy provides various logging and monitoring options to help you troubleshoot issues. You can configure MySQL Proxy to log queries, errors, and other events to a file or send them to a remote logging system.

Additionally, you can use tools like mysql-proxy-admin to inspect the status of MySQL Proxy and its backends. This can be helpful for monitoring performance, identifying bottlenecks, and debugging problems.

Remember to consult the official MySQL Proxy documentation for more detailed information on configuring and using MySQL Proxy, as well as examples of Lua scripts and advanced configuration options.